Sharif Digital Repository

Different information theories have been provided in recent decades because of the numerous applications of information notion in different fields of sciences. Meanwhile, pragmatic theory of information is one of the most common concepts in this field which has been studied remarkably in recent decades. Different aspects of this theory (in J. G. Roederer’s sense of attitude) are critically assessed in this thesis. Roederer considers the information as a relative concept in which interaction plays fundamental role. Moreover, information is an agent which leads to an univocal correspondence between the sender and the recipient, so that the presence of a certain spatial or temporal pattern... 

According to modal interpretations of quantum mechanics, a state possesses definite values even if it is not an eigenstate. On the other hand, Kochen-Specker theorem holds that all possible possessed values by a system can not be definite. Consequently, modal interpretations to block this theorem, take new metaphysics of properties. In this dissertation, I will show that dispositionalism is that metaphysics. According to dispositionalism, causal powers of a property are constituents of the property. As regards this outline, the thesis would be divided into 5 chapters. In chapter one, presuppositions of later arguments are clarified. Chapter two is related to algebra of properties and finally... 

Cognitive radio is a tool for optimal use of radio spectrum, not used by the primary users all the time. Two main features of a cognitive radio are cognitive capability and reconfigurability. An intelligent cognitive radio uses its cognition ability to identify the environmental parameters and makes future decisions based on this information. Then the reconfigurability is used to set the sending parameters to the calculated values in the cognition phase. Cogition phase consists of major steps; spectrum sensing, decision, mobility and handoff. Throughout this thesis we first propose a cooperative sensing scheme using algorithmic techniques based on sensors’ spatial information through... 

Bohm-de Broglie theory is an alternative for standard quantum mechanics for explaining the bizarreness of micro-phenomena. This theory is casual and deterministic,but endows with nonlocal and contextual characters. Up to now,two different approaches presented: One is known as Bohm-Hiley (BH) formalism and the other is Dürr-Goldstein-Zanghí (DGZ) representation. In BH formalism, quantum potential has a significant role, according to witch peculiar phenomena such as quantum tunneling, two-slit interference and chemical bond are explained. Active information is also another important rotion introduced by quantum potential. In DGZ approach, however, the foundation of Bohm theory is based on... 

Classical methods in aircraft conceptual aircraft design have some deficiencies in such as low accuracy in aerodynamic derivatives estimation and incapability of verifying flight handling quality. Moreover, application of experimental equations and dependence on statistical data are other drawbacks of classical methods which are accounted as big challenges in development of unusual aircrafts. In this research, a comprehensive, rapid and practical software is developed in order to promote the conceptual aircraft design. This software provides a platform to perform various tasks such as aerodynamic measurement, nonlinear simulation, system identification and optimization simultaneously. In... 

Bohm theory is an alternative for standard quantum mechanics which, provides a deterministic description for physical microsystems. In this theory every physical system, describes as a quantum particle which guided by a correspondiente wave. In stationary states every wave-particle, depends on its initial conditions, is at rest in different points. As an example in hydrogen atom, stationary states means electron, with constant radius and polar angle, has a circular motion in planes which is parallel with xy plane. In this thesis the stationary trajectories of hydrogen atom has been reconsidered and new trajectories are sketched. Also by extension the discussion to the macrosystems, we study... 

Heat exchangers are one of the most important components used in liquefaction cycles and overall efficiency of the cycle mainly depends on the heat exchangers effectiveness. It has been shown that the effectiveness of these equipments should be high enough to be able to liquefy a gas. Spiral heat exchangers are used frequently in cryogenic industry and specially in Helium liquefaction industry due to their specific characteristics, however according to literature review it turns out that little study is done in the field of simulation and geometrical parameter investigation of these kind of heat exchangers, so in this study the design and simulation of these cryogenics heat exchangers are... 

Inhencemant of automobile radiator heat performance is the purpose of this study. Radiator fin shape, coolant fluid properties and influence of nanofluid studied in this research. Plain fin, louvered fin and vortex generator fin is choosen and design. With flow simulation influence of fin shape on heat performance is studied. After that, with considering radiator coolant fluid, the effect of antifreezing on fin heat transfer is evaluated. Then by addin nanoparticles to water and antifreezing solution, effect of nanofluid on heat transfer is evaluated. Results show that with increasing the air velocity for all geometries in the study , heat transfer and pressure drop is increased. But heat... 

This project examines time in quantum mechanics, which includes three chapters. The first chapter is about clocks, which first deals with the history and invention of clocks, and then goes on to describe quantum clocks and various theories about them, including Perez and Faraday quantum clocks . The second chapter deals with the two-slit Yang experiments which, as in the preceding chapter, we first give a historical description of the experiment, and we will continue with our description. We consider that for each of these cases the probability of spatial and linear momentum interference is calculated. The third chapter is the final chapter. In this section, we first discuss the concept of... 

The aim of this study is to develop a new algorithm to perform high performance and precise maneuvers for variety of fixed-wing UAVs. Iterative learning in conjunction with an adaptive control technique is developed here for this purpose. In this research, the guidance and control laws are initially developed by classic algorithms that exist in most of commercial autopilot systems. Then, the learning algorithm is combined with the classic autopilot system to improve trajectory tracking performance. The algorithms have been tested by simulation in the loop technique, utilizing Simulink and X-Plane software. So, the navigation data was provided by the X-Plane, solving dynamic equations, and... 

In this study, in order to enhance the accuracy of tracking repetitive maneuvers in Unmanned Aerial Vehicles (UAVs), an educable control scheme is proposed. At the outset, the controller is designed based on the sliding mode control (SMC) technique. In addition, the offline PD-type memory-based iterative learning control (ILC) is used along with SMC. In ILC scheme, the error of states is saved during the maneuvers that will be used in the subsequent iteration. Also, in order to increase flexibility of the new control structure, ILC-SMC, a multilayer perceptron has been developed. This network is designed to extend the control signal, generated by ILC, to similar maneuvers. The presented... 

Cryogenic temperature is below than 123 Kelvin and any physical study that occurs below this temperature is Cryogenic science. Cryogenic has varaiety of application in medical, industry, food, oil and gas etc. Based on this paper and its relavant source spiral wound HE is one of the most optimum HE for cryogenic application specially for helium liquification cycle. In order to liquefy helium in helium cycle efficiency of spiral wound HE shall be over than 85 percent. For this reason and special fluid behavour in low temperature considering property variation, heat in leak and axial conduction is vital for calculating efficiency in cryogenic temperature of helium liquification cycle. In this... 

In this thesis, a framework for measuring the relative dynamic similarity and multi-fidelity design of the dynamic similar model of aircraft is presented. The conditions for establishing dynamic similarity between the scaled model and the original aircraft have been investigated for different applications and the methods for establishing relative dynamic similarity have been studied. In related researches conducted in the field of designing similar dynamic models of flying devices, the degree of relative similarity has not been measured and usually one or more scaling laws have been omitted according to the type of application. In this thesis, it has been shown that partial dynamic... 

Improving performance and reducing costs is a constant competition between aircraft designers, which has made multi-disciplinary optimization always part of the design process. In the design process of a conventional aircraft, there are various uncertainties in technology levels, mission parameters, costs and operating environment. It is clear that these uncertainties will make the decision-making difficult and lead to uncertainties in the output of the design; on the other hand, considering them will increase the computational cost. Understanding how much the uncertainty of each parameter will affect the overall output of the design and its performance, makes it possible to ignore the... 

The role of data in the advancement of science and engineering has been emphasized due to the abundance and verity of data, the improvement in online computing speed, the enhancement of quality of life in the era of cyber-physical systems, human aspirations for new discoveries, and the need for real-time decision-making in autonomy. Furthermore, the emergence of new computing capabilities has created additional demands for data. Utilizing data-based methods has become a necessity, as the system model is not always available or cannot be represented as a comprehensive mathematics. System modeling can be extremely challenging and complex, which can hinder controller performance or even render... 

Freeze desalination as a water refining method has attracted a lot of attention due to its potential in lowering process energy consumption compared to other methods. This method is based on the fact that the dissolved salt is drained from the saline water during its freezing. The current study conducts a parametric study on freezing saline water in a cylindrical container to investigate the impact of geometric and functional factors affecting the desalination quality. This has been done by examining the aforesaid factors in the form of dimensionless parameters such as thermal Grashof number, solutal Grashof number, and Jacob number. In addition, in order to improve the desalination, a novel... 

In this thesis we are going to explore a new formalism in micro domain which describes quantum phenomena in a realistic casual fashion by introducing an unified concept of matter, energy, and Information. In this theory, a micro-entity, e.g. an electron, is a combination of a particle and its associated field integrated to a new entity called particle-field. The dynamics of such system will be analyzed. Then, some quantum examples which have controversial aspects will be discussed within the new theory. In a generalized form of formalism, the non-linear Schrödinger Equation is introduced, which enables us to predict some experimental data for common Quantum Mechanical stationary systems.... 

Cognitive radio (CR) technology is envisaged to solve the problems in wireless networks resulting from the limited available spectrum and the inefficiency in the spectrum usage by exploiting the existing wireless spectrum opportunistically. CR networks, however, impose unique challenges due to the high fluctuation in the available spectrum as well as diverse quality-of-service (QoS) requirements. Specifically, in cognitive radio ad hoc networks (CRAHNs), the distributed multi-hop architecture, the dynamic network topology, and the time and location varying spectrum availability are some of the key distinguishing factors. In this literature, we propose a new routing algorithm that tries to... 

Cost Estimation plays an essential and role in UAV (Unmanned Aerial Vehicles) Projects. By increasing the complexity of new unmanned systems, the importance of this task augments. Additionally, up to now, a comprehensive approach has not been adopted internationally. But in parallel a number of international companies and organizations has developed specific methods by themselves; confined to their corporate.
This project pursues developing a complexity-based model for cost estimation of unmanned aerial vehicles, especially Jet UAVs. However, it’s anticipated that this model may be utilized for all kind of systems, but it seems that jet UAVs use it with a better and more reliable... 

Wireless communication applications need high computing power, flexibility and scalability. Although ASICs have the ability of high computing power but they are not flexible to changing or completing of communication protocols. On the other hand, general purpose microprocessors or DSPs are flexible, but do not provide sufficient computing power. Thus devices with reconfigurable architecture have been proposed as a compromise between ASICs and microperocessors. One of the main features of reconfigurable devices is the granularity. The granularity of a reconfigurable devices shows the amount of computing power incorporate in a processing element. In this thesis we have evaluated different...